The present invention relates to a slicing machine used when thin silicon wafers are cut from a silicon ingot, and a control method thereof.
In a slicing machine, various cutting techniques are used. For example, in a conventional technique, a cutting tool having a circular inner peripheral cutting edge is mounted on a tool mounting base and is rotated, and the rotating cutting tool is fed relative to a work or the work is fed relative to the cutting tool, thereby cutting the work. In this cutting technique, thin silicon wafers can be efficiently cut from a silicon ingot.
However, in the cutting technique, the cutting edge is deformed, in other words, flexed in the direction of the rotational axis due to a cutting resistance caused by a change in cutting arc length between the cutting edge and the work, so that straightness of the cut surface of the cut work is impaired.
For this reason, in a conventional slicing machine, the flexure of the blade is measured during cutting of the work, and if the measured flexure is increased, the cutting speed is decreased to improve the straightness of cutting, as disclosed in Japanese Utility Model Laid-Open Publication (unexamined) No. 62-70904.
However, in the conventional arrangement, since the rotational speed of the blade is constant, even if the cutting speed is decreased, a force for correcting the flexure direction of the blade is insufficient, and surface precision of the work cut surface cannot be easily improved.